Classifications

• • C—CHEMISTRY; METALLURGY
  • C07—ORGANIC CHEMISTRY
  • C07D—HETEROCYCLIC COMPOUNDS
  • C07D251/00—Heterocyclic compounds containing 1,3,5-triazine rings
  • C07D251/02—Heterocyclic compounds containing 1,3,5-triazine rings not condensed with other rings
  • C07D251/12—Heterocyclic compounds containing 1,3,5-triazine rings not condensed with other rings having three double bonds between ring members or between ring members and non-ring members
  • C07D251/14—Heterocyclic compounds containing 1,3,5-triazine rings not condensed with other rings having three double bonds between ring members or between ring members and non-ring members with hydrogen or carbon atoms directly attached to at least one ring carbon atom
  • C07D251/16—Heterocyclic compounds containing 1,3,5-triazine rings not condensed with other rings having three double bonds between ring members or between ring members and non-ring members with hydrogen or carbon atoms directly attached to at least one ring carbon atom to only one ring carbon atom

Definitions

• the present invention relates to a process for preparing asymmetrically substituted triazines of the general formula I ##STR3## where R 1 is hydrogen, methyl or ethyl, R 2 and R 3 independently of one another are a hydrocarbon radical having 1 to 6 C atoms, which can carry substituents which are inert under the reaction conditions, by reaction of a cyanoguanidine of the formula II ##STR4## with a carboxylic acid derivative in the presence of an alcohol of the formula III
• Asymmetrically substituted triazines can be prepared in a great variety of ways, eg. starting from N-cyanoamides by reaction with Vilsmeier complexes (R. L. N. Harries, Aust. J. Chem. 34 (1981) 623), from N-cyanoimidate esters (DE-A 34 11 202; M. A. Perez, J. L. Soto, Heterocycles, 20 (1983) 463; K. R. Huffman, F. C. Schaefer, J. Org. Chem. 28 (1963) 1816) or from biguanidines (S. L. Shapiro et al, J. Org. Chem. 25 (1960) 379; U.S. Pat. No. 2,535,968).
• zinc sulfate forms a chelate complex which after working up by boiling in water decomposes in a second reaction step to give the sulfate of amidino-O-methylisourea (U.S. Pat. No. 3,360,534, IN-A 167 500) and this can be reacted in a third reaction step with acetic anhydride (S. Lotz, G. Kiel, G. Gattow, Z. anorg. allg. Chem. 604 (1991) 53-62) or with methyl trifluoroacetate (T. Tsujikawa, Yakugaku Zasshi 95, loc. cit) to give the triazine in yields of 31 and 26% respectively.
• acetic anhydride S. Lotz, G. Kiel, G. Gattow, Z. anorg. allg. Chem. 604 (1991) 53-62
• methyl trifluoroacetate T. Tsujikawa, Yakugaku Zasshi 95, loc.
• R 3 has the abovementioned meaning and R 4 is a hydrocarbon radical having 1 to 6 C atoms, which can carry substituents which are inert under the reaction conditions, in the presence of a base or of a carboxamide selected from the group consisting of N,N-di(C 1 -C 4 -alkyl)formamide, N,N-di(C 1 -C 4 -alkyl)acetamide and N-methylpyrrolidone and in the presence of a salt or of a salt-like compound of the elements magnesium, calcium, aluminum, zinc, copper, iron, cobalt, nickel or chromium.
• a base or of a carboxamide selected from the group consisting of N,N-di(C 1 -C 4 -alkyl)formamide, N,N-di(C 1 -C 4 -alkyl)acetamide and N-methylpyrrolidone and in the presence of a salt or of a salt-like compound of the elements magnesium, calcium
• the substituted cyanoguanidine used as a starting substance is generally known.
• the N-methyl- and N-ethyl-substituted derivatives are available from cyanoguanidine and dialkyl sulfate as described by A. E. Kretov and A. S. Bespalyi in Zhur. Prik. Khimii, Vol. 34, (1961) 621ff.
• the guanidine can also be employed in the form of an acid addition salt, in this case the acid set free during the reaction expediently being neutralized by addition of a suitable base such as sodium methoxide.
• hydrocarbon radical in the triazine I aliphatic, cycloaliphatic, aromatic or araliphatic radicals having up to 8 carbon atoms such as C 1 -C 8 -alkyl, C 3 -C 8 -alkenyl, C 3 -C 8 -alkynyl, C 3 -C 8 -cycloalkyl and also phenyl, benzyl or phenethyl are to be mentioned in particular for R 2 .
• R 2 is, for example, C 1 -C 4 -alkyl such as methyl, ethyl, n-propyl, isopropyl, n-butyl, sec-butyl or tert-butyl; C 3 -C 4 -alkenyl such as prop-2-en-1-yl, 1-methylprop-2-en-1-yl, but-2-en-1-yl or but-3-en-1-yl; C 3 -C 4 -alkynyl such as prop-2-yn-1-yl or but-2-yn-1-yl; C 3 -C 6 -cycloalkyl such as cyclopropyl, cyclobutyl, cyclopentyl or cyclohexyl; particularly preferably C 1 -C 4 -alkyl such as methyl.
• C 1 -C 4 -alkyl such as methyl, ethyl, n-propyl, isopropyl, n-but
• the radical R 2 can in turn carry still further substituents which are inert under the reaction conditions, such as eg. fluorine or chlorine, phenyl, C 1 -C 4 -alkyl, C 1 -C 4 -haloalkyl or C 1 -C 4 -alkoxy.
• the carboxylic acid ester radical R 4 has the meaning mentioned above for R 2 and is preferably identical to R 2 .
• R 3 is widely variable. It can have eg. the meanings specifically mentioned for R 2 .
• R 3 is preferably C 1 -C 4 -haloalkyl, in particular fluoro- or chloromethyl or -ethyl such as CCl 3 , CF 3 , CF 2 CF 3 , CF 2 Cl, CFCl 2 , CH 2 Cl, CHCl 2 , CH 2 F and CHF 2 .
• Perhalogenated alkyl radicals such as CCl 3 , CF 3 and C 2 F 5 are particularly preferred.
• the reaction of the cyanoguanidine II with the alcohol III (or R 4 OH, formed by hydrolysis of the ester IV) is carried out in the presence of a base.
• the reactivity of the metal chelate complexes can be increased by this means such that the reaction with the esters IV is possible, even though these esters are less reactive by far than corresponding carboxylic anhydrides or orthoesters.
• Suitable bases are inorganic and organic bases.
• Preferred inorganic bases are alkali metal and alkaline earth metal hydroxides
• preferred organic bases are tertiary amines such as C 1 -C 4 -trialkylamine, eg. triethylamine, pyridine or N-methylmorpholine.
• the alkali metal or alkaline earth metal alkoxide of the alcohol R 2 OH to be reacted is expediently used as a base. This alkoxide can also be formed in situ, eg. from the corresponding alkali metal or sodium amide or sodium hydride and the alcohol III.
• the amount of base is customarily from 0.1 to 2, in particular from 0.8 to 1.2, mole equivalents, based on the cyanoguanidine II. Larger amounts are possible, but as a rule provide no further advantages.
• a carboxamide from the group consisting of N,N-di(C 1 -C 4 -alkyl)formamide, N,N-di(C 1 -C 4 -alkyl)acetamide or N-methylpyrrolidone can also be used instead of the base or additionally. Examples which may be mentioned are dimethylformamide, diethylformamide, dimethylacetamide and diethylacetamide.
• the addition of carboxamides has proven particularly suitable when using heavy metals, in particular copper, as chelating agents.
• the amount of carboxamide is in general from 1 to 30, in particular from 5 to 10, mole equivalents, based on the cyanoguanidine II. It may also be advantageous to utilize the carboxamide as a solvent.
• Suitable salts or salt-like compounds of the alkaline earth metals, of aluminum or of the heavy metals are products readily soluble in the reaction medium, such as halides, eg. fluorides, chlorides or bromides, nitrates, sulfates or possibly phosphates, alkoxides or acetates. According to present knowledge, apart from good solubility the type of alkaline earth metal compound or metal compound does not matter, so that, inter alia, cost considerations are decisive in the choice.
• Examples which may be listed are the following compounds: MgCl 2 , Mg(OCH 3 ) 2 , CaCl 2 , Zn(NO 3 ) 2 , Cu(CH 3 COO) 2 , AlCl 3 , AlBr 3 , ZnCl 2 , ZnBr 2 , CuCl 2 , NiBr 2 , CrCl 3 , CaO, Ca(NO 3 ) 2 , MS(NO 3 ) 2 , MgO, ZnO, FeCl 2 , FeCl 3 , Fe(NO 3 ) 2 , Fe(NO 3 ) 3 .
• the chlorides, in particular CaCl 2 and ZnCl 2 are particularly preferred.
• One advantage of the process according to the invention is that the presence of heavy metals can be largely or completely dispensed with and, for ecotoxicological reasons, less unacceptable elements such as magnesium and in particular calcium can be avoided. Soluble salts of these elements are therefore particularly preferred. Very good results are also achieved, however, with zinc compounds.
• the salts or salt-like compounds of the abovementioned elements can be employed in stoichiometric amounts or preferably less than stoichiometric amounts, based on the cyanoguanidine II, eg. in amounts of from 0.001 to 2 mol, in particular from 0.005 to 1.0 mol per mole of II.
• the particularly preferred amount is from 0.01 to 1.0, in particular from 0.05 to 0.5 mol.
• stoichiometric amounts based on II, eg. from 1 to 2 mol per mole of II, can be employed, but reasons of economy are a point in favor rather of employing substoichiometric amounts.
• the starting substance III can be formed in situ from the carboxylic acid ester IV (R 2 ⁇ R 4 ) or is added to the reaction mixture (preferably as a solvent).
• the starting material III simultaneously as a solvent, it is recommended to select the alcohol component in the ester IV accordingly (ie. R 2 ⁇ R 4 ) in order to avoid by-products.
• the molar ratio of cyanoguanidine II to the alcohol III is in general from 1 to 30, in particular from 5 to 10.
• the carboxylic acid ester IV is expediently used in an amount of from 0.5 to 10, in particular from 1 to 5 mol, per mole of cyanoguanidine II.
• the esters IV to be mentioned are particularly preferably the following compounds:
• C 1 -C 4 -alkane- or haloalkanecarboxylic acid esters such as methyl acetate, ethyl acetate, methyl propionate, ethyl propionate, methyl trifluoroacetate, methyl difluoroacetate, methyl fluoroacetate, methyl trichloroacetate, methyl dichloroacetate, methyl chloroacetate, ethyl trifluoroacetate, (m)ethyl pentafluoropropionate and (m)ethyl pentachloropropionate.
• methyl trifluoroacetate and ethyl trifluoroacetate are particularly preferred as starting substances IV.
• reaction of II with III and IV can be carried out in substance, ie. without addition of inert solvents.
• the alcohol R 2 OH is simultaneously used as a solvent.
• the corresponding alkoxide is then selected as a base.
• the reaction temperature is from 0° to 200° C., in particular from 20° to 150° C., particularly preferably the reflux temperature of the reaction mixture.
• reaction is carried out at atmospheric pressure or under the autogenous pressure of the particular reaction medium.
• the reaction can be carried out continuously and also batchwise.
• the reaction components are preferably passed through a tubular reactor or a stirred tank reactor cascade.
• the triazine I is prepared without isolation of intermediates.
• the cyanoguanidine II, the ester IV and less than the stoichiometric amounts of the alkaline earth metal salt or of the metal salt (or salt-like compounds) into the alcohol R 2 OH as a solvent, metering in the base, eg. the alkali metal alkoxide such as NaOR 2 or KOR 2 and heating the mixture to reflux.
• the reaction is terminated in a customary manner when cyanoguanidine can no longer be detected in the reaction mixture (eg. by means of thin-layer chromatography, high pressure liquid chromatography or gas chromatography).
• the crude products obtained can be further purified if desired, eg. by crystallization, rectification or by means of chromatographic methods.
• triazines I which can be prepared in a simple manner by the process according to the invention are useful intermediates for the synthesis of dyestuffs, drugs and crop protection agents, in particular herbicides, as described eg. in the publications EP-A 508 348, EP-A 111 442 or DE-A 40 38 430.
• the volatile constituents are removed in a water-jet vacuum at a bath temperature of 40° C., the residue is partitioned between 100 ml of water and 100 ml of ethyl acetate, and the organic phase is separated off and dried over MgSO 4 .

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• Chemical & Material Sciences (AREA)
• Organic Chemistry (AREA)
• Plural Heterocyclic Compounds (AREA)
• Organic Low-Molecular-Weight Compounds And Preparation Thereof (AREA)
• Preparation Of Compounds By Using Micro-Organisms (AREA)
• Low-Molecular Organic Synthesis Reactions Using Catalysts (AREA)
• Catalysts (AREA)
• Pharmaceuticals Containing Other Organic And Inorganic Compounds (AREA)

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• 1993
  • 1993-10-19 DE DE4335497A patent/DE4335497A1/de not_active Withdrawn
• 1994
  • 1994-10-10 DE DE59404115T patent/DE59404115D1/de not_active Expired - Lifetime
  • 1994-10-10 JP JP51126695A patent/JP3805359B2/ja not_active Expired - Lifetime
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  • 1994-10-10 CZ CZ19961016A patent/CZ289450B6/cs not_active IP Right Cessation
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  • 1994-10-10 WO PCT/EP1994/003331 patent/WO1995011237A1/de active IP Right Grant
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  • 1994-10-10 RU RU96112138A patent/RU2125995C1/ru active
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• 1996
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• 1997
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